Turbine system



Aug M, w45- .1. s. HAvERsTlcK v 2,382,564

TURBINE SYSTEMS l Filed Sept. 16, 1943 2 Sheets-Sheet l Patented Aug. 14, 1945 UNITED STATEs `rirrau'r OFI-ics 'TURBINE SYSTEM/f' John S. Haverstlck, Trenton, N. J., assignor to De Laval Steam Turbine Company, Trenton, N. .I 'a corporation of New Jersey Application September 16, 1943, Serial No. 502,600

4 Claims.

Thisinvention relates to a combustion turbine system and has particular reference to the apl 'the mechanical strength of the turbine rotors at their high speeds of operation. It has been proposed, therefore, as set fortli in the patent 'to Birmann No. 2,283,176, dated ,May 19, 1942,

to introduce into passages in turbine rotorscooling air for the purpose of maintaining the blades at safe operating temperatures. 'As disclosed in said Birmann patent, it is possible to eilect this cooling in eiiicient fashion by providing air passages which at their inlet portions act as impellers to compress the air and at their outlet portions as turbine passages in which the heated air is expanded to high discharge velocity, so serving to impart rotational impulse to the wheels.

For single stage turbines, suchan arrangement is-very satisfactory. In the case of multistage turbines, however, since the coolin'g air must, in practical installations, become admixed with the .driving gases exhausted from the rst stage, the average temperature of the gases reaching the second stage is quite substantially reduced. It has been proposed to apply heat to the mixed air and gases passing from the first turbine, but since the volume of total gas is large and since the oxygen content is substantially less than that of atmospheric air, diillculties are involved in securing proper combustion in reasonable space.

In accordance with the present invention, an arrangement is provided in which the combustion of auxiliary fuel takes place in cooling air prior to its substantial admixture with the combustion gases, so that the temperature of the cooling air may be raised to or higher than the temperature of the gases exhausted from the first stage turbine. This arrangement may, of course, be repeated in successive stages in a turbine system having more than two stages.

Combustion of auxiliary fuel may take place not only in air but in relatively cool combustion gases, which may contain an excess of air, such as ilow through radially inner passagesl in a multiow turbine of the type disclosed in my application Serial No. 501,102,v filed September 3, 1943.

The above general object of -the invention, as well as further objects relating particularly to details, will become apparent from the following description, read in conjunction with the accompanying drawings, in which:

Figure 1 shows diagrammatically a turbine system provided in accordance with the invention; and

Figure 2 shows a similar diagram of a modiiled arrangement.

A turbine rotor of the type described in said Birmann patent is illustrated at 2, being provided with buckets 4. formed in its' metal rotor disc, into which driving gases are directed through nozzles 6 from a gas chest 8 receiving combustion gases from an internal combustion engine, burner, or the like, there being conventionally illustrated a combustion chamber at I0 in which fuel from a nozzle l2 is burned. The auxiliary parts of the system have no bearing on the present invention, consequently there are not illustrated the compressor and associated parts which would normally be involved in supplying air toa burner of the type illustrated. The turbine 2, which constitutes the rst stage, discharges its gases into a tail passage I6 through guide vanes'or struts, indicated at I2, which support an annular guard I4 providing a temporary inner boundary to vthe stream of discharged gases.

For the purpose of cooling the turbine, passages are provided having the compressor portions I8 and discharge portions 20 operating in accordance with the principle set forth in said Birmann patent. These passages may be localized adjacent the roots of the turbine vanes as indicated, .being conventionally formed as intersecting drilled or bored openings,`though they may take various forms depending upon the particular turbine design. The passage I8 receives air from the regionv22 vsurrounding the turbine shaft, and the air, after compression and absorption of heat from the rotor, is discharged at high velocity rearwardly from the portion 20 of each cooling passage into the region inside the guard I4, so that temporarily, as it leaves the turbine, it is separated from the combustion gases discharging from the turbine buckets.

A nozzle 34 introduces auxiliaryfuel into this air and, as will be evident from the drawings, the

spray or jet of fuel is intimately mixed with the air, so that complete combustion may be effected substantially before any appreciable admixture of the air with the combustion gases takes place. In this Way the region of combustion is very substantiallyl reduced, since in the less oxygenated gases from the turbine discharge v the combustion region would be very considerably extended before combustion was completed. A baffle 35 serves to protect the rotor from the heat of combustion of the fuel introduced at 34. The mixture of gases discharged from the first stage turbine and the products of combustion, and excess air resulting from the cooling and the burning of auxiliary fuel, flow by way of the passage 24 to the` gas chest 26 of the second stage turbine 32, being introduced into the buckets I oi the latter through the nozzles 2B. While not so illustrated, this turbine may, of course, also be provided with cooling air and, if desired, ad ditional fuel may be introduced as inthe-case of the first turbine for supplying supplemental energy to still another stage.

While the particular relationship of the twostage turbines is not important s0 fares the present invention is concerned, it may be pointed out that in installations of this type the two turbines 'may operate mechanically independently of each other. Thelhigh pressure stage, for example, may drive compressors or other auxiliary equipment, while the mechanical power takeofi may be from the second stage. This arrangement may be reversed, however, with the power take-off from the first stage. In any event, it will be evident that control of the fuel introduced as indicated gives rise to auxiliary control for the second stage, the power developed therebybeing controlled either by this alone or by auxiliary control of the low pressure turbine ow. I

The cooling air is held to the pressurecf they hot gases discharged from the turbine buckets and expansion losses which would occur if the air expanded to atmospheric pressure are avoided. An increase of mass flow of gas to the second stage occurs by reason of the present arrangement.

Figure 2 shows an arrangement very similar to that of Figure 1 but providing for the better control of the auxiliary combustion and of the ultimate admixture of the combustion gases fed to the turbine with the products resulting from the auxiliary combustion. As in the previous modification, the turbine wheel 40 is provided wlth combustion gases from a chest 42, the buckets of the turbine discharging this gas into the annular passage M outside the annular guard 50. rIhe cooling air flowing through passages 46 passes, upon expansion, into the region 48 inside the guard 50. The auxiliary fuel is injected at 52, but combustion thereof is controlled by reason of the provision of an inner guide member 5B which A admits at first only some of the air to the fuel,

additional air being progressively added in the form of annular flow sheets'through the passages deiined inwardly and outwardly of an annular guide vane 56. The combustion gases from the passage M are also guided to control their admixture with the products from the interior of the guard 50 by means of annular guide vanas 58 and 60. In this fashion the combustion is properly controlled to effect addition of heat at the correct rate to secure its most efflcient addition. The mixed gases, as in the case of the previous modification, pass to a second stage turbine.

Reference has been made in connection with the modifications heretofore described to the use case, the hotter combustion gases flow at an outer radius while the cooler combustion gases, which in the present instance, may contain an -excess of air, have a path of flow inwardly of the hot gases and may be directed to a burner of the type described in which fuel may be burned there in prior to their admixture with the hotter gases. The combined gases may then pass to a later stage turbine. Where, therefore,in the following claims reference is made to acooler gas, it will be understood that that gas may be air or may be a mixture of combustion gases with air capalble of supporting further combustion of fuel.

It will be evident that the invention is applicable in general to axial flow turbines in which the air or cooler gas passages may not have increasing, and then decreasing,'radii.

What is claimed is:

1. In combination, a turbine having a rotor provided with buckets, means for directing hot gases to the turbine buckets for driving the rotor, passages in the rotor for gas having a temperature lower than said hot gases and capable of supporting combustion, said cooler gas becoming eventually mixed with said hot driving gases as the latter flow from the buckets, and means for burning auxiliary fuel in the cooler gas discharged from said passages prior to substantial admixture thereof With. Said driving EBSES.

' ing auxiliary fuel in the cooler gas discharged the turbine ibeing of a multiow type. In such from said passages prior to, substantial admixture thereof with said driving gases, a second turbine,

and means for leading the mixed gases to the second turbine.

3. In combination, a turbine having a rotor provided with buckets, means for directing hot combustion gases to the turbine buckets for driving the rotor, paages in the rotor for gas having a temperature lower than said combustion gases and capable of supporting combustion, said passages having impeller portions for effecting compression of the cooler gas and discharge portions for effecting expansion thereof after heating, said cooler gas becoming eventually mixed with said hot driving gases as the latter flow from the buckets, and means for burning auxiliary fuel in said cooler gas discharged from said passages prior to substantial admixture thereof with said driving gases.

4. In combination, a turbine having a rotor provided with buckets, means for directing hot combustion gases to the turbine buckets for driving the rotor, passages in the rotor for gas having a temperature lower than said combustion gases and capable of supporting combustion, said passages having impeller portions for effecting compression of the cooler gas and discharge portions for. effecting expansion thereof after heating, said cooler gas becoming eventually mixed with said hot driving gases as the latter flow from the buckets, means for burning auxiliary fuel in said cooler gas discharged from said passages prior to substantial admixture thereof with said driving gases, a second turbine, 4and means for leading the mixed gases to the second turbine.

JOHN S. HAVERSTICK. 

